diff options
| author | Tom Lane | 2004-05-23 03:50:45 +0000 |
|---|---|---|
| committer | Tom Lane | 2004-05-23 03:50:45 +0000 |
| commit | ebfc56d3fb41d914c799555a1f4c9d1a72379e9f (patch) | |
| tree | 7fb674efed5b26eb9a11b0e77733b2c8e7eaf642 /src/include/storage/pmsignal.h | |
| parent | 4d86ae42600c42834a55371630416e98593b7b11 (diff) | |
Handle impending sinval queue overflow by means of a separate signal
(SIGUSR1, which we have not been using recently) instead of piggybacking
on SIGUSR2-driven NOTIFY processing. This has several good results:
the processing needed to drain the sinval queue is a lot less than the
processing needed to answer a NOTIFY; there's less contention since we
don't have a bunch of backends all trying to acquire exclusive lock on
pg_listener; backends that are sitting inside a transaction block can
still drain the queue, whereas NOTIFY processing can't run if there's
an open transaction block. (This last is a fairly serious issue that
I don't think we ever recognized before --- with clients like JDBC that
tend to sit with open transaction blocks, the sinval queue draining
mechanism never really worked as intended, probably resulting in a lot
of useless cache-reset overhead.) This is the last of several proposed
changes in response to Philip Warner's recent report of sinval-induced
performance problems.
Diffstat (limited to 'src/include/storage/pmsignal.h')
| -rw-r--r-- | src/include/storage/pmsignal.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/include/storage/pmsignal.h b/src/include/storage/pmsignal.h index e8ba72a253f..688b83adab1 100644 --- a/src/include/storage/pmsignal.h +++ b/src/include/storage/pmsignal.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.6 2003/11/29 22:41:13 pgsql Exp $ + * $PostgreSQL: pgsql/src/include/storage/pmsignal.h,v 1.7 2004/05/23 03:50:45 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -24,7 +24,7 @@ typedef enum { PMSIGNAL_DO_CHECKPOINT, /* request to start a checkpoint */ PMSIGNAL_PASSWORD_CHANGE, /* pg_pwd file has changed */ - PMSIGNAL_WAKEN_CHILDREN, /* send a NOTIFY signal to all backends */ + PMSIGNAL_WAKEN_CHILDREN, /* send a SIGUSR1 signal to all backends */ NUM_PMSIGNALS /* Must be last value of enum! */ } PMSignalReason; |